上緣偶氮苯及下緣β-胺基-α,β-不飽和酮取代芳杯之合成及其金屬離子感測研究

Abstract

本研究主要分為四個研究主題，分別探討上緣偶氮苯或下緣beta-胺基-alpha,beta-不飽和酮基取代的芳杯對於金屬離子的錯合能力。 在第一章中，我們合成出一系列以丙烯基與偶氮苯修飾上緣的芳杯 43、44、45a-b 和 46a-b，探討偶氮苯與丙烯基在芳杯上緣空間上的排列， 對於錯合 Hg2+ 能力的影響。結果顯示偶氮芳杯與 Hg2+ 錯合能力大小為 Ka (42a) > Ka (42b) > Ka (43) > Ka (44) > Ka (45a) > Ka (45b) > Ka (46a) > Ka (46b)。此結果說明了對位甲氧基取代的偶氮苯與丙烯基在芳杯上緣的排列 方式，採對位雙取代的空間排列對 Hg2+ 的錯合能力較強 (如芳杯42a)。此 外，我們亦利用共振拉曼光譜的實驗，證實偶氮芳杯 43 與 Hg2+ 離子錯 合時，形成了醌□苯腙的結構。在第二章，我們合成能同時錯合陽離子與陰離子的雙螯合接受器芳杯 74。利用 Mo(CO)6 對下緣 isoxazole 取代芳杯 73 進行開環反應即可得 beta-胺基-alpha,beta-不飽和酮基團取代芳杯 74。利用紫外可見光與螢光光譜探討芳 杯 73 和 74 對金屬離子的錯合能力。芳杯 73 和 74 為對 Cu2+ 有高選擇 性的化學感測器。當加入 Cu2+ 離子時，芳杯 73 的螢光會被淬熄，而芳杯 74 則為螢光增強。從 EPR 的實驗證明， Cu2+ 離子與芳杯 73 和 74 錯 合時，會與苯酚或beta-胺基-alpha,beta-不飽和酮基團發生氧化還原反應，而形成 Cu+ 離子。當芳杯 74 與 Cu+ 錯合後，可協助錯合 F□ 和CH3COO□ 離子， 而造成螢光增強效應。在第三章，我們合成芳杯 92b，其下緣取代為beta-胺基-alpha,beta-不飽和酮 和醯胺基團。初步金屬離子篩選結果顯示，芳杯 92b 對 Cu2+、Hg2+ 和 Pb2+ 離子有辨識效果，其中以 Cu2+ 所造成的螢光增強效應最明顯。芳杯 92b 可同時辨識兩當量的 Cu2+，其可能錯合位置推測為 (1) 雙邊的beta-胺基-alpha,beta-不飽和酮基團和 (2) 下緣苯酚與醯胺基間的互相協助。其錯合常數 為 2.02 x 109 M-2。且從 EPR 實驗得知，Cu2+ 會被芳杯 92b 還原成 Cu+。 控制化合物 93 和 96b 對 Cu2+ 的錯合研究亦支持 92b 與 Cu2+ 的可能 iii 錯合模式 在第四章，我們合成了1,3-alternate 構形芳杯 104，分別在下緣修飾beta-胺基-alpha,beta-不飽和酮基和蒽基取代的三唑基團。初步的研究結果顯示，Li+、 Na+ 和 K+ 錯合在beta-胺基-alpha,beta-不飽和酮基位置，而 Pb2+、Cu2+、Hg2+ 和 Cr3+ 等離子不但影響了吸收度的變化，也造成的螢光的淬熄，推測應是beta-胺基-alpha,beta-不飽和酮基和三唑基團兩部分皆有錯合現象。未來，將進行金屬 離子間的競爭效應。並合成控制化合物 109 及 110 比較其與金屬離子間 的錯合效應

In this thesis, we investigated the binding abilities of calix[4]arenes substituted with upper-rim azophenyl groups or lower-rimbeta-amino-alpha,beta-unsaturated ketones toward metal ions. In chapter 1, we described the synthesis of a series of upper-rim p-allyl- and p-phenylazo substituted calix[4]arenes 43, 44, 45a-b and 46a-b. We expected that these ligands might show some specific stereoselectivity toward Hg2+ ion. The results showed that the binding abilities of calix[4]arenes toward Hg2+ followed the order: Ka (42a) > Ka (42b) > Ka (43) > Ka (44) > Ka (45a) > Ka (45b) > Ka (46a) > Ka (46b). It implied that the two p-methoxyphenylazo and the two p-allyl groups prefered to bind Hg2+ in a distal orientation (such as 42a). Furthermore, the resonance Raman spectrum of 43·Hg2+ supported the formation of quinone-hydrazone tautomer. v In chapter 2, we reported a new ditopic calix[4]arene receptor 74 for the simultaneous complexation of anionic and cationic species. The host molecule 73 was synthesized first, followed by Mo(CO)6 mediated ring–opening reaction which gave the target receptor calix[4]arene 74. The binding properties of ligands 73 and 74 in acetonitrile toward metal ions were investigated by UV□vis and fluorescence spectroscopies. The results showed that both ligands 73 and 74 were highly selective to recognize Cu2+ ion. Upon titration with Cu2+, the fluorescence of 73 was severely quenched, whereas, 74 showed a strong fluorescence enhancement. According to EPR experiments, the Cu2+ was reduced to Cu+ by the free phenolic□OH or beta-amino-alpha,beta-unsaturated keton, during the complexation of 73 and 74 with Cu2+. Ditopic behaviour was observed for the complex 74·Cu+ which showed further enhancement on its fluorescence intensity upon complexation with anions such as acetate or fluoride. In chapter 3, we synthesized a Cu2+ induced fluorescence turn-on sensor, calix[4]arene 92b, which contains amide groups linkedbeta-amino-alpha,beta-unsaturated ketone units with naphthalene pendant as the fluorophore. Calix[4]arene 92b can recognize Cu2+, Hg2+ and Pb2+, in which Cu2+ induced a remarkable fluorescence enhancement. The binding ratio between 92b and Cu2+ was 1:2, and the two possible binding sites for Cu2+ in 92b were conjectured to be: (1) at vi the low-rim phenolic-OH and amide groups, and (2) at the beta-amino-alpha,beta-unsaturated ketones. The association constant (Ka) of the 1:2 complex 92b·2Cu+ was calculated to be 2.02 × 109 M-2. Futhermore, according to EPR experiments, the Cu2+ was reduced to Cu+ by the free phenolic□OH and beta-amino-alpha,beta-unsaturated ketone, during the complexation of 92b with Cu2+. The binding studies of control compounds 93 and 96b toward Cu2+ also supported the proposed binding mode of 92b with Cu2+. In chapter 4, we report the synthesis of a chemosensor based on 1,3-alternate calix[4]arene 104 containing two different cationic binding sites, constructed by anthrylmethyl-triazole and β-amino-α,β-unsaturated ketone groups. Preliminary studies of UV-vis and fluorescence measurements on 104 toward metal ions showed that Li+, Na+ and K+ might be bound with β-amino-α,β-unsaturated ketone, whereas Pb2+, Cu2+, Hg2+ and Cr3+ might be bound with triazole and/or β-amino-α,β-unsaturated ketone. In the future, we will also investigate the allosteric effect of 104 for metal ions by UV-vis, fluorescence, and 1H NMR spectroscopy. The control compounds 109 and 110 will be synthesized for comparison.